Lead roller for elastomeric threads



May 16, 1967 w. GOLLOS LEAD ROLLER FOR ELASTOMERIC THREADS Filed Feb. 12, 1965 TAKE UP SPOOL ZERO TENSION LSETTING EXIRUSION BATH NOZZLE INVENTORr WOLFGANG GOLLOS BY Y 123 MJ 004 ATT 'YS United States Patent O LEAD ROLLER FOR ELASTOMERIC THREADS Wolfgang Gollos, Klingenberg am Leisbaum, Germany,

assignor to Vereinigte Glanzstofl-Fabriken AG., Wuppertal-Elberfeld, Germany Filed Feb. 12, 1965, Ser. No. 432,330 Claims priority, applicatiirgi Gelrmany, Feb. 15, 1964,

8 9 10 Claims. (Cl. 18-8) This invention relates to a lead roller which is adapted to deliver or convey elastomeric threads, and more particularly, the invention is concerned with a roller used to deliver a freshly spun elastomeric thread onto a takeup spool or bobbin.

When winding ordinary threads onto a take-up spool, it is known that so-called lead or delivery rollers can be employed in order to place tension on the thread as it runs onto the spool and to maintain this tension as uniform as possible. In general, these lead rollers of known construction have a rough or notched surface for contact with the thread, whereby slippage between the thread and the roller surface are to be prevented. The thread tends to conform to the irregular profile of this rough surface and thereby increases its frictional adherence to the lead roller. It is thus possible to provide favorable conditions for regulation of the thread tension between the lead roller and the point at which winding occurs on the takeup spool.

In winding freshly spun elastomeric threads, however, conventional roller constructions cannot be used because it is essential in this case to prevent the elastomeric thread and the roller surface from having the same velocity. The rough surface of the conventional roller causes the thread to cling or adhere to this surface, so that different velocities cannot be achieved and there is interference with the proper delivery of the thread during transport to the winding or take-up spool. In view of this unsatisfactory performance of known rollers with elastomeric threads, it was deemed necessary to find another means in combination with the winding operation which would provide a satisfactory delivery and winding of such threads.

For example, an attempt was made to use a lead roller having a completely smooth surface in the form of a running groove similar to the usual construction of a cord or rope pulley. It has been proven, however, that the frictional relationships in such a pulley-type roller are completely uncontrollable. The elastomeric thread sometimes adheres to the roller surface and at other times exhibits only a very slight frictional adherence. In the latter case, the thread is no longer conveyed or delivered by the roller, or else the rate of delivery is insufficient with respect to the winding velocity.

It is an object of the present invention to solve the basic problem of transporting or delivering a freshly spun elastomeric thread to a take-up spool or other winding device by means of a novel lead roller.

Another object of the invention is to provide a lead roller which will transport the elastomeric thread in a uniform manner and in such a way that the thread can be wound on the take-up spool or bobbin substantially without longitudinal tension, i.e. Without stretching the thread during winding on the spool.

Still another object of the invention is to provide a lead roller which can be positively rotated at a rate faster than that corresponding to the longitudinal speed of the thread, so as to achieve a differential velocity between the contact surface of the roller and the thread itself. At the same time, the lead roller must accelerate the transported elastomeric thread sufficiently to provide ice a thread tension between the roller and the take-up spool which is approximately equal to zero.

Yet another object of the invention is to provide a lead roller in which the frictional adherence of the freshly spun elastomeric thread is carefully controlled to give a uniform delivery of the thread to the take-up spool without interruption of the continuous winding operation.

Another object of the invention is to provide a single, inexpensive and easily constructed lead roller which can be readily combined with conventional thread Winding apparatus.

These and other objects and advantages of the invention will become more apparent upon consideration of the following detailed specification.

It has now been found, in accordance with the invention that it is possible to substantially improve the conveyance and winding of freshly spun elastomeric threads by means of a hollow cylindrical lead roller having an annular groove in its outer circumferential surface, this groove being smoothly rounded at least on the radially inwardly recessed base portion thereof which is in running contact with the thread. The groove also contains a plurality of openings distributed at substantially uniformly spaced intervals over the entire circumference of the recessed base portion, the openings extending inwardly as a hollow space to receive excess liquid, preferably as a fluid passageway extending from the groove to a larger hollow space in the roller. In this novel lead roller, the radius of the rounded base portion of the groove should be at least about four times and preferably at least five times the thread diameter. Also, the best results have been achieved when the proportion of the total circumferential surface area of the base portion of the groove occupied by the openings is about /3 to The lead roller or delivery roller of the invention is used in combination with conventional thread winding apparatus which essentially requires a take-up spool mounted on a drive shaft with any suitable means to rotate and regulate the velocity of the spool. The lead roller is likewise mounted on a drive shaft with means to regulate its peripheral velocity to exceed the peripheral velocity of the take-up spool, thereby permitting the elastomeric thread to be fed or delivered from the lead roller to the take-up spool under substantially zero tension.

In essence, the lead roller of the invention solves the basic problems of receiving a freshly spun elastomeric thread and transporting it in a completely uniform manner to the take-up spool or similar winding device so that the thread can be wound in its normal relaxed state, i.e. practically without longitudinal tension. In order to achieve a differential speed between the lead roller and the thread, the periphery of the roller corresponding to the bottom or base portion of the groove must rotate faster than the linear speed of the thread in contact with the smooth grooved surface. At the same time, however, there must be sufiicient frictional contact between the thread and the roller so that the roller accelerates the thread just enough during transport to the take-up spool to provide a thread tension between the roller and point of winding which is approximately equal to zero.

A study of the frictional relationships between the thread and roller surface has shown that the coefficient of friction is primarily determined on the one hand by the adhesiveness of the freshly spun thread on smooth surfaces and on the other hand by the film which is formed by excess liquid on the thread and carried along between the thread and the roller surface. It was then found that the frictional relationship could be controlled and kept substantially constant only if openings are provided in accordance with the invention to interrupt the otherwise continuous grooved surface and to permit liquid being carrried by the thread to fiow off the grooved surface, preferably being discharged through a hollow passageway in liquid connection with the groove and the hollow space inside the roller.

The base portion of the groove in the roller of the invention essentially corresponds to that surface which will come in contact with the running thread. The width of this base portion can therefore be varied depending upon the size or diameter of the thread to be accommodated. The series of openings around the circumference of the groove can be conveniently made by drilling or boring radial holes or cylindrical passageways through a grooved annular ring, and this ring can then be connected to cylindrical side plates on either side, at least one of these side plates being journaled and preferably provided with a sleeve extension for mounting on the drive shaft. The inner diameter of the grooved annular ring can be sufficiently larger than the diameter of the drive shaft to provide a large hollow space in the interior of the assembled roller.

The invention is further illustrated by but not limited to the specific embodiments of a lead roller as shown in the accompanying drawing wherein:

FIG. 1 is a perspective view of one embodiment of a lead roller constructed in accordance with the invention;

FIG. 2 is an enlarged diametric cross-sectional view of the lead roller shown in FIG. 1;

FIG. 3 is a diametric cross-sectional view of the annular ring portion of the roller corresponding to FIGS. 1 and 2, there being a semi-circular groove in this annular ring;

FIG. 4 is a diametric cross-sectional view of another embodiment of the annular ring containing a wedgeshaped groove around its circumference; and

FIG. 5 is a schematic illustration of the manner in which an elastomeric thread is extruded and wound onto a take-up spool with the aid of the lead roller according to the invention.

In FIGS. 1, 2 and 3 of the drawing, the drive shaft 1 is mounted in any suitable manner so as to be positively rotated at a regulated rate. The lead roller 2 according to the invention is attached to this drive shaft 1 and is constructed to provide an annular groove 3 of semicircular cross-section, this groove serving to maintain running contact with the e-lastomeric thread. This groove 3 contains a series of openings or radial bores 4 which are equidistantly spaced from each other and which extend completely around the circumference of the groove. The roller can be constructed as a single integral element, but in a preferred embodiment of the invention, the groove and openings are contained in an annular ring 3' which is held in place between two cylindrical flanges or side plates 5 and 6. One of these side plates 5 preferably includes a sleeve extension or mounting stub 7 with any suitable means for firmly connecting the roller to the drive shaft 1.

In the preferred construction as shown in FIG. 2, the annular ring 3, is attached to side plate 6 by means of at least two screws 8 connecting the inner annular flange 9 which is composed of a ferromagnetic material with a low remanence. Side plate 5 contains permanent magnets 10 mounted firmly on its inner face portion so that the outer half of the roller composed of side plates 6, annular ring 3' and annular flange 9 is actually held in place to the inner half or side plate 5 by magnetic force. .The purpose of this construction and a more complete description thereof is contained in my copending application, filed concurrently herewith.

As shown in FIG. 3, the openings or radial bores 4 in the annular ring 3' have a diameter d which is equal to the bottom or lower base portion of the groove providing surface contact with the running thread. Of course, the diameter of the holes or openings may extend laterally beyond the base portion of the grove, and it is also feasile to employ elliptical or rectangular openings even though these are apt to be more difficult to form in the manufacture of the roller. In all cases, the bridge surfaces in running contact with the thread between the openings are smoothly rounded transversely as well as in the circumferential direction of the groove. While this transverse radius of curvature should be at least four or five times the diameter of the thread, it is preferable for ease in manufacture to form a semi-circular groove of larger radius similar to that shown in FIG. 3. A somewhat different embodiment of the annular ring is shown in FIG. 4 where the groove is in the shape of a wedge with a smoothly rounded bottom portion containing the openings and upper sides which diverge rectilinearly outwardly. These and other shapes and configurations of the groove and the openings can be made without departing from the spirit or scope of the invention.

The ratio of the smooth surface of the grove acting as a bridge between the openings to the corresponding total surface occupied by the openings can be varied Within relatively wide limits. It has proved to be particularly advantageous, however, to use a range in which the ratio of the total bridge surfaces to that of the openings is about 2:1 to 1:3. In other words, the openings should occupy about one-third to three-quarters of the total circumferential surface of the base portion of the groove in running contact with the thread. If one then uses circular openings having a diameter equal to the width of the lower base portion, the total number of holes or openings can be readily calculated according to the formula n=4D/3d to 3D/d, where D is the diameter of the annular groove. In other words, the total number of holes or openings 12 is a value corresponding approximately to the diameter of the annular groove divided by the diameter of each opening up to three times this value. For example, if d=0.2 inch, D 3 inches and the openings should occupy one-half the total surface of the base portion of the groove, the formula is n=2D/d or n=30 openings which are equidistantly spaced around the peripher of the groove.

By using an annular ring segment 3' in the lead roller, a relatively large open or hollow space is provided in the interior of the roller which is capable of receiving liquid which collects from the freshly spun elastomeric thread onto the smooth running surface of the groove and then runs off through the openings or passageways 4. At the same time, a small amount of liquid tends to remain on the running surfaces of the groove, but in a relatively constant amount so as to provide a uniform regulation of the adhesion of the thread for the running surface of the groove. On the other hand, the openings themselves appear to cooperate with the smooth bridging surfaces of the groove, not only in removing excess liquid but also in improving the adhesion of the thread to the roller without gripping it so tightly as to prevent the desired slippage or differential velocity between the thread and the roller. In any event, the lead roller according to the invention does permit the elastomeric thread to be transported or delivered under substantially zero tension and without irregular fluctuations in adhesion and velocity as experienced with previous rollers.

The manner in which the lead roller is combined with a take-up spool in the extrusion of elastomeric threads is quite well known in the art, and FIG. 5 merely provides a schematic illustration of this combination wherein the thread T is delivered by the lead roller from the setting bath to the take-up spool under substantially zero tension. Conventional means are employed for rotating the spool and the roller, and it is also possible to co-employ other known regulating devices for adjusting the rotational velocity of the roller and/ or the spool in response to the tension being placed on the thread. With otherwise conventional apparatus, it has been found desirable to mount the lead roller at a distance of about 20 to 50 cm. in front of the take-up spool, with reference to the direction of the running thread. It is essential, of course, to rotate the lead roller with a peripheral velocity which exceeds the peripheral velocity of the take-up spool in order to prevent stretching of the thread between the roller and the spool.

When using the lead roller of the invention in combination with other conventional thread winding apparatus, it becomes possible to carry out the winding of a freshly spun elastomeric thread in an efficient and trouble-free manner. The lead roller is therefore especially adapted to the commercial production of any of the various known natural and synthetic rubber threads as they are spun or extruded in the form of a rubber latex, solidified in a setting bath and subsequently wound onto a take-up spool. After the winding has been completed, the resulting package of elastomeric thread is quite uniform and tensionfree in its winding structure.

The invention is hereby claimed as follows:

1. A lead roller for conveying a freshly spun elastomeric thread which comprises a hollow cylindrical roller having an annular groove in its outer circumferential surface, said groove being transversely smoothly rounded at least on the radially inwardly recessed peripheral portion thereof which is in running contact with said thread, and containing a plurality of openings distributed at substantially uniformely spaced intervals over the entire circumference of said recessed peripheral portion, said openings extending inwardly from said groove to the hollow space in said roller.

2. A lead roller as claimed in claim 1 wherein the radius of the rounded recessed peripheral portion of said groove is at least about four times the thread diameter.

3. A lead portion as claimed in claim 1 wherein the proportion of the total surface area of the recessed peripheral portion of said groove occupied by said openings is about /3 to 4. A lead roller as claimed in claim 3 wherein the radius of the rounded recessed peripheral portion is at least about five times the thread diameter.

5. Thread winding apparatus comprising; a take-up spool mounted on a drive shaft and adapted to receive a freshly spun elastomeric thread to be wound into a thread package; means to rotate said take-up spool at a regulated velocity; a hollow cylindrical lead roller mounted on a drive shaft and having an annular groove in its outer circumferential surface with at least the radially inwardly recessed peripheral portion of said groove being transversely smoothly rounded to receive said thread in running contact therewith for transport of said thread to said take-up spool, the radius of said rounded recessed peripheral portion being at least four times the diameter of the thread, and said groove containing a plurality of openings distributed at spaced intervals over the entire circumference of said recessed peripheral portion, said openings providing a fluid passageway inwardly to the hollow space of said roller for removal of excess liquid from the freshly spun thread; and means to rotate said roller at a regulated peripheral velocity exceeding the peripheral velocity of said take-up spool.

6. Thread winding apparatus as claimed in claim 5 wherein the proportion of the total surface area of the recessed peripheral portion of said groove occupied by said openings is about /3 to 7. Thread winding apparatus as claimed in claim 5 wherein said lead roller is mounted at a distance of about 20 to cm. before the take-up spool, with reference to the direction of thread travel.

8. Thread winding apparatus as claimed in claim 5 wherein said groove has a semicircular-shaped cross-section.

9. Thread winding apparatus as claimed in claim 5 wherein said groove has a wedge-shaped cross-section.

10. In an apparatus for producing an elastomeric thread including spinning means to extrude and solidify an elastomeric thread in a liquid setting bath and a take-up spool adapted to receive the freshly spun thread for winding into a thread package, the improvement comprising:

a hollow cylindrical lead roller adapted to receive said thread as it emerges from said setting bath and to convey said thread onto said take-up spool, said roller having an annular groove in its outer circumferential surface with at least the radially inwardly recessed peripheral portion of said groove being transversely smoothly rounded to receive said thread in running contact therewith, and said groove containing a plurality of openings distributed at spaced intervals over the entire circumference of said recessed peripheral portion, said openings extending inwardly from said groove to the hollow space within said roller.

References Cited by the Examiner UNITED STATES PATENTS 2,246,917 6/1941 Francis 242--45 2,284,244 5/1942 Allquist 242-45 2,871,502 2/1959 Whisnant 226- X STANLEY N. GILREATH, Primary Examiner, 

1. A LEAD ROLLER FOR CONVEYING A FRESHLY SPUN ELASTOMERIC THREAD WHICH COMPRISES A HOLLOW CYLINDRICAL ROLLER HAVING AN ANNUYLAR GROOVE IN ITS OUTER CIRCUMFERENTIAL SURFACE, SAID GROOVE BEING TRANSVERSELY SMOOTHLY ROUNDED AT LEAST ON THE RADIALLY INWARDLY RECESSED PERIPHERAL PORTION THEREOF WHICH IS IN RUNNING CONTACT WITH SAID THREAD, AND CONTAINING A PLURALITY OF OPENINGS DISTRIBUTED AT SUBSTANTIALLY UNIFORMELY SPACED INTERVALS OVER THE ENTIRE CIRCUMFERENCE OF SAID RECESSED PERIPHERAL PORTION, SAID OPENINGS EXTENDING INWARDLY FROM SAID GROOVE TO THE HOLLOW SPACE IN SAID ROLLER. 